A preferred way of handling the millions of pounds of polyurethane scrap, which are generated each year, is to decompose the resin into its basic constituents -- a polyol and an amine which is typically a diamine. Potentially, this decomposition process is a primary step in recycling these basic materials. One method of decomposing a polyurethane resin is to expose it to superheated steam at a temperature in the range of from about 500.degree. F. to 650.degree. F. One product of this decomposition is an amine rich aqueous vapor. However, this product contains not only amines and steam but also a variety of other products in particulate, liquid and vapor form; typically the amines are in the vapor phase. Thus, the problem is one of cooling this vapor and recovering amines; this, of course, must be done under conditions which will prevent the amines from undergoing any degradative chemical reaction such as oxidation.
Traditionally, this type of recovery problem has been solved by either distillation or a liquid extraction process. However, both of these processes would require an intermediate step of condensing the vapor. In developing the most efficient process it was decided that a spray condenser could be used to condense the vapor and at the same time initiate a solvent extraction process. Thus, the impinging spray in the condenser would contain water and a suitable solvent. For this process to be successful, the solvent would have to meet the following criteria. First, it would have to have a high solvating power for the desired amine products. Second, it would have to have a high boiling point; that is greater than 120.degree. C.; and, third, it must be able to protect the amine products against oxidation. In addition to these requirements, it was learned that the extracting solvent would also have to have either a strong affinity for or the ability to repulse the particular contaminants in the original vapor product to promote a clean interface when the organic and aqueous phases separate.
Unfortunately, most common solvents, such as chloroform, methylene chloride and ethyl acetate, failed in the latter respect, and the particulate contaminants were able to collect at the interface and diffuse it to such a degree that it was extremely difficult to separate the phases.